Hemostatic composition

ABSTRACT

The present invention relates to improved hemostatic compositions comprising cellulose-based fibers supplemented with compounds, preparation and use thereof.

FIELD OF THE INVENTION

The present invention relates to improved hemostatic compositionscomprising cellulose-based fibers supplemented with compounds.

BACKGROUND OF THE INVENTION

In a wide variety of circumstances, animals, including humans, cansuffer from bleeding due to wounds or during surgical procedures. Insome circumstances, the bleeding is relatively minor, and normal bloodclotting in addition to the application of simple first aid, are allthat is required. In other circumstances substantial bleeding can occur.These situations usually require specialized equipment and materials aswell as personnel trained to administer appropriate aid. Bleeding duringsurgical procedures may manifest in many forms. It can be discrete ordiffuse from a large surface area. It can be from large or smallvessels, arterial (high pressure) or venous (low pressure) of high orlow volume. It may be easily accessible or it may originate fromdifficult to access sites.

Conventional methods to achieve hemostasis include use of surgicaltechniques, sutures, ligatures or clips, and energy-based coagulation orcauterization. When these conventional measures are ineffective orimpractical, adjunctive hemostasis techniques and products are typicallyutilized.

The selection of appropriate methods or products for the control ofbleeding is dependent upon many factors, which include but are notlimited to bleeding severity, anatomical location of the source, theproximity of source to adjacent critical structures, whether thebleeding is from a discrete source or from a broader surface area,visibility and precise identification of the source and access to thesource.

Many products have been developed as adjuncts to hemostasis. Theseproducts include topical absorbable hemostats (TAH) such as oxidizedregenerated cellulose, gelatin in various forms with or without athrombin solution, collagen powder, biologically active topicalhemostatic products (topical thrombin solutions, fibrin sealants, etc.),and a variety of synthetic topical sealants.

Topical Absorbable Hemostats (TAHs) are widely used in surgicalapplications. TAHs encompass products based on oxidized cellulose (OC),oxidized regenerated cellulose (ORC), gelatin, collagen, chitin,chitosan etc. To improve the hemostatic performance, scaffolds based onthe above materials can be combined with biologically-derived clottingfactors such as thrombin and fibrinogen.

One of the most commonly used topical hemostatic agents is SURGICEL®Original absorbable hemostat, made from oxidized regenerated cellulose(ORC). ORC was introduced in 1960 as a safe and effective hemostaticagent for many surgical procedures. SURGICEL® Original is a loose knitORC fabric that conforms rapidly to its immediate surroundings and iseasier to manage than other absorbable agents because it does not stickto surgical instruments and its size can be easily trimmed. This allowsthe surgeon to hold the cellulose firmly in place until all bleedingstops.

The control of bleeding is essential and critical in surgical proceduresto minimize blood loss, to reduce post-surgical complications, and toshorten the duration of the surgery in the operating room. Due to itsbiodegradability and its bactericidal and hemostatic properties,oxidized cellulose, as well as oxidized regenerated cellulose have longbeen used as a topical hemostatic wound dressing in a variety ofsurgical procedures, including neurosurgery, abdominal surgery,cardiovascular surgery, thoracic surgery, head and neck surgery, pelvicsurgery, and skin and subcutaneous tissue procedures. A number ofmethods for forming various types of hemostats based on oxidizedcellulose materials are known, whether made in powder, woven, non-woven,knitted, and other forms. Currently utilized hemostatic wound dressingsinclude knitted, woven, or non-woven fabrics comprising oxidizedregenerated cellulose (ORC), which is oxidized cellulose with increasedhomogeneity of the cellulose fiber.

SURGICEL® absorbable hemostats are used adjunctively in surgicalprocedures to assist in the control of capillary, venous, and smallarterial hemorrhage when ligation or other conventional methods ofcontrol are impractical or ineffective. The SURGICEL® family ofabsorbable hemostats consists of four main product groups, with allhemostatic wound dressings commercially available from Ethicon, Inc.,Somerville, N.J., a Johnson & Johnson Company: SURGICEL® Originalhemostat is a white fabric with a pale yellow cast and a faint, caramellike aroma. This material is strong and can be sutured or cut withoutfraying;

SURGICEL® NU-KNIT® absorbable hemostat is similar to SURGICEL® Originalbut has a denser knit and thus a higher tensile strength, this materialis particularly recommended for use in trauma and transplant surgery asit can be wrapped around or sutured in place to control bleeding;SURGICEL® FIBRILLAR™ absorbable hemostat product form has a layeredstructure that allows the surgeon to peel off and grasp with forceps anyamount of material needed to achieve hemostasis at a particular bleedingsite, and therefore, may be more convenient than the knitted form forhard to reach or irregularly shaped bleeding sites. It is particularlyrecommended for use in orthopedic/spine and neurological surgery;SURGICEL® SNoW™ absorbable hemostat product form is a structurednon-woven fabric that may be more convenient than other forms forendoscopic use due to the structured, non-woven fabric, and is highlyadaptable and recommended in both open and minimally invasiveprocedures.

Another example of a commercial absorbable hemostat containing oxidizedcellulose is GELITA-CEL® absorbable cellulose surgical dressing fromGelita Medical BV, Amsterdam, The Netherlands. The commerciallyavailable oxidized cellulose hemostat noted above is available inknitted, nonwoven fabrics or powder form. Additional hemostaticproducts, such as powders consisting of microporous polysaccharideparticles and plant starch based particles, are also commerciallyavailable as PERCLOT® and ARISTA™.

Other background related references include:

-   U.S. Pat. No. 8,815,832; U.S. Pat. No. 3,364,200; US2008/0027365;    US2004/0005350; WO2007/076415; U.S. Pat. No. 6,627,749; U.S. Pat.    No. 6,309,454; U.S. Pat. No. 5,696,191; U.S. Pat. No. 6,627,749;    U.S. Pat. No. 6,225,461; WO2001/024841A1; EP1,323,436;    US2006/0233869. U.S. Pat. No. 5,645,849A; U.S. Pat. No. 5,643,596A;    WO1996040033A1; U.S. Pat. No. 5,484,913A; U.S. Pat. No. 9,131,929B2;    U.S. Pat. No. 8,722,081B2; U.S. Pat. No. 7,923,031B2; U.S. Pat. No.    6,056,970A; U.S. Pat. No. 4,749,689A; U.S. Pat. No. 4,637,815A;    US20150017225A1; US20130310873A1; US20120253298A1 US20090062233A1;    US20080138387A1; US20020192271A1; EP1641399B1; EP1731175B1;    EP2233157A1; EP2203053A1; WO1990013320A1; CA2688196C;    AU2013218367B2; CN104013991A; CN1850111A; RU2235539C1; U.S. Pat. No.    5,403,278A; PH32014A; WO2002024239A1.-   Howsmon, J. A., & Marchessault, R. H. (1959). The ball-milling of    cellulose fibers and recrystallization effects. Journal of Applied    Polymer Science J. Appl. Polym. Sci., 1(3), 313-322.    doi:10.1002/app.1959.070010308.-   Cullen, B., Watt, P. W., Lundqvist, C., Silcock, D., Schmidt, R. J.,    Bogan, D., & Light, N. D. (2002). The role of oxidised regenerated    cellulose/collagen in chronic wound repair and its potential    mechanism of action. The International Journal of Biochemistry &    Cell Biology, 34(12), 1544-1556. doi:10.1016/s1357-2725(02)00054-7.-   Rajkhowa, R., Wang, L., & Wang, X. (2008). Ultra-fine silk powder    preparation through rotary and ball milling. Powder Technology,    185(1), 87-95. doi:10.1016/j.powtec.2008.01.005. Yasnitskii, B. G.,    Dol'berg, E. B., Oridoroga, V. A., Shuteeva, L. N., Sukhinina, T.    V., & Bogun,-   T. A. (1984). Oxycelodex, a new hemostatic preparation.    Pharmaceutical Chemistry Journal, 18(4), 279-281.    doi:10.1007/bf00760712.

SUMMARY OF THE INVENTION

The present invention relates to improved hemostatic compositionscomprising fibers, originated from a cellulose source material,supplemented with compounds.

In one aspect, the invention provides a hemostatic compositioncomprising: cellulose-based fibers having a size distribution of D90 ofless than 350 μm, and D50 of less than 167 μm, the fibers are at aconcentration range of 83.5%-90.0% w/w of the entire composition; anomega amino carboxylic acid at a concentration range of 2.5%-5.0% w/w ofthe entire composition; protamine salt at a concentration range of2.5%-5.0% w/w of the entire composition; a divalent cation, the cationconcentration being 1.3%-1.8% w/w of the entire composition, wherein thecomposition is in the form of a powder and/or aggregates.

In some embodiments the composition of the invention also comprisesfibers of size 350 μm.

Size distribution D50 is also known as the median diameter or the mediumvalue of the units in the powder/aggregates size distribution, it is thevalue of the units' diameter at 50% in the cumulative distribution. Forexample, if D50 is X μm, then 50% of the units in the sample are largerthan X μm, and 50% are smaller than X μm. Size distribution is thenumber of units that fall into each of the various size ranges given asa percentage of the total number of all units' sizes in the sample ofinterest. Accordingly, D90 value refers to 90% of the units having asize that is smaller than the D90 value. All ranges disclosed hereininclude the upper and lower limit, where applicable.

In one embodiment, the cellulose-based fibers have a size distributionof D90 of less than 177 μm and D50 of less than 95 μm.

In a further embodiment, the cellulose-based fibers are OxidizedRegenerated Cellulose (ORC) fibers.

In another further embodiment, the omega amino carboxylic acid isEpsilon Amino Caproic Acid (εACA).

In some embodiments, the protamine salt is protamine sulfate.

In some embodiments, the divalent cation salt is provided by calciumchloride.

In some embodiments, the concentration ranges of εACA, protaminesulfate, and calcium chloride are 2.5%-5.0%, 2.5%-5.0%, 5.0%-6.5% w/w,respectively, and wherein the remaining weight is contributed by thecellulose-based fibers to a total weight of 100% w/w.

In some embodiments, a gel formed from the powder composition uponcontact with blood has a resistance of equal to or higher than 10 timesthat of a gel formed upon contact of a comparative powder compositionconsisting of Oxidized Regenerated Cellulose (ORC) with blood; and/orwherein a gel formed from the aggregates composition has a hemostaticcapability of equal to or higher than 1.5 times that of a gel formedupon contact of a comparative aggregates composition consisting of ORCwith blood.

In some embodiments, the composition is in the form of aggregates havinga size in the range of 75 μm-420 μm.

In another aspect, the invention provides a method for making ahemostatic composition comprising the steps of: mixing cellulose fibershaving a size distribution of D90 of less than 350 μm, and D50 of lessthan 167 μm, the fibers being at a concentration range of 83.5%-90% w/wof the entire composition with the following powder compounds:

i—an omega amino carboxylic acid at a concentration range of 2.5%-5.0%w/w of the entire composition;ii—protamine salt at a concentration range of 2.5%-5.0% w/w of theentire composition; andiii—a divalent cation, the cation concentration being 1.3%-1.8% w/w ofthe entire composition.

In some embodiments, the fibers have a size distribution of D90 of lessthan 177 μm, and D50 of less than 95 μm.

In another aspect, the invention provides a hemostatic compositionobtainable according to the method of the invention.

In some embodiments, the method further comprises the steps of:compacting the hemostatic composition; and optionally, subjecting thecompacted composition to drying, and size reduction, thereby obtaininghemostatic aggregates.

In another aspect, the invention provides a hemostatic aggregatescomposition obtainable according to the method of the invention.

In another aspect, the invention provides a method for forming a gelcomprising the step of:

contacting a hemostatic powder and/or aggregates composition accordingto the invention with blood, thereby forming a gel.

In one embodiment, when the contacting is carried out with the powdercomposition, the formed gel has a resistance of equal to or higher than10 times that of a gel formed upon contact of a comparative powdercomposition consisting of Oxidized Regenerated Cellulose (ORC) withblood;

and/or wherein when the contacting is carried out with the aggregatescomposition, the formed gel has a hemostatic capability of equal to orhigher than 1.5 times that of a gel formed upon contact of a comparativeaggregates composition consisting of ORC with blood.

In another aspect, the invention provides a gel obtainable by the methodaccording to the invention.

In another aspect, the invention provides a kit comprising a containerincluding a hemostatic composition according to the invention andoptionally an applicator, carrier and/or instructions for use.

In another aspect, the invention provides a method of treating ableeding wound; a bacterial infection at a wound site, minimizing orpreventing a leak from an anastomotic site; sealing a leak at a siteand/or preventing adhesion at a surgery site in a subject in need, themethod comprising applying an effective amount of the hemostaticcomposition according to the invention onto and/or into the wound and/orsite of the subject.

The subject can be a human patient or an animal.

In another aspect, the invention provides use of a hemostaticcomposition according to the invention for the treatment of a bleedingwound; a bacterial infection at a wound site, minimizing or preventing aleak from an anastomotic site; sealing a leak at a site and/orpreventing adhesion.

In one embodiment, the use is for minimizing or preventing a leak in acoronary artery bypass graft (CABG) surgery.

In one embodiment the application is carried out without applyingpressure on the composition towards the wound and/or site. For examplemanual compression using a gauze is not necessary. In various productsthe product requires manual compression during application for at leasta minute. The advantage of using the hemostatic composition withoutcompression is that the hemostatic composition can be applied in/on hardto reach areas.

BRIEF DESCRIPTION OF FIGURES

FIGS. 1 and 2 are bar graphs showing the resistance force/cohesivestrength obtained from the different powder compositions using amodified Bloom test. The resistance force obtained from non-supplementedfine ORC fibers served as a baseline for the entire experiment.

FIG. 3 is a bar diagram showing the hemostatic efficacy of anon-compacted and compacted powder composition (i.e. composition in theform of aggregates) and the effect of calcium ions in the compactedcomposition by an ex-vivo suture model.

DETAILED DESCRIPTION

The invention relates to improved hemostatic composition(s), in powderand/or aggregates form, comprising cellulose-based fibers, supplementedwith compounds.

The invention relates to powder and/or aggregates composition(s) havingsurprising physical properties and highly beneficial effect(s) forhemostasis upon gel or clot formation; to their preparation and usethereof. For example, the powder and/or aggregates composition inducegel or clot formation having beneficial physical properties, such asincreased cohesive strength, and beneficial hemostatic capability.

The hemostatic composition comprises fibers originated from acellulose-based material and supplemented with compounds; thecomposition is in the form of powder and/or aggregates.

The term “cellulose-based fibers” relates to fibers comprising acellulose backbone. The cellulose backbone can be modified, for example,it may include alterations in carboxylation or oxidation levels. Nonlimiting examples of cellulose-based materials include oxidizedcellulose or oxidized regenerated cellulose, Carboxymethyl cellulose,Hydroxyethyl cellulose, Hydroxypropyl cellulose and Methylcellulose.

Non limiting examples of cellulose-based fibers are ORC fibers, Cottonfibers, Rayon fibers, and Viscose fibers.

Cellulose-based fibers can be made from cellulose-based materials. Nonlimiting examples of cellulose-based materials are woven, non-woven,knitted, and/or other forms of fabrics.

The term “fibers” relate to structures having elongated threadlike form.

The term “powder” relates to dispersed dry solid particles.

In one embodiment, a powder composition according to the inventionincludes fibers and supplementary compounds in particulate form.

The term “aggregates” relates to compacted cellulose-based material,such as powder and/or fibers, having a target size range e.g. thecompacted material is subjected to size reduction such as milling andoptionally sieving. In one embodiment aggregates are compacted powdercomposition subjected to size reduction such as milling.

Non limiting examples of size reduction are milling, grinding, shreddingand/or tearing.

The term “hemostatic” relates to the ability to reduce bleedingintensity or to arrest bleeding.

The hemostatic composition can be prepared by mixing cellulose-basedfibers with omega amino carboxylic acid, protamine salt, and a divalentcation in ranges according to the invention.

Omega amino carboxylic acid can be as ω-carboxylic acid with variablechain lengths including but not limited to 2-aminoaceticacid (glycine),3-aminopropanoic acid, 4-amino butanoic acid, 5-aminopentanoic acid,6-aminohexanoic acid 7-aminoheptanoic acid, 8-amino octanoic acid,9-aminononanoic acid, 10-aminodecanoic acid, and c aminocaproic acid.

In one embodiment of the invention the protamine salt in the compositionis protamine sulfate. Other examples of protamine salts include, but arenot limited to, protamine amine.

In one embodiment of the invention, the divalent cation in thecomposition is provided by calcium chloride. Other examples of divalentcation salts include, but are not limited to, magnesium chloride,calcium acetate and iron(II) chloride.

In one embodiment of the invention the concentration ranges of εACA,protamine sulfate, and calcium chloride are 2.5%-5.0%, 2.5%-5.0%,5.0%-6.5% w/w, respectively, and the remaining weight of the compositionis contributed by the cellulose-based fibers to a total weight of 100%w/w.

The hemostatic composition can further comprise an additive selectedfrom the group consisting of carboxymethyl cellulose, an anti-infectiveagent, another hemostasis promoting agent, gelatin, collagen, orcombinations thereof.

In some embodiments of the invention, the hemostatic compositionsfurther includes carboxymethyl cellulose (CMC) or other polysaccharides,anti-infective agents, hemostasis promoting agents, gelatin, collagen,or combinations thereof.

Non limiting examples of fibers' source material or cellulose-basedmaterial to be used as a starting material to make the fibers for thecomposition include: oxidized regenerated cellulosic fabric, oxidizedregenerated cellulose (ORC), woven, knitted, non-woven fabric, shreddedoxidized regenerated cellulosic material or combinations thereof.

According to the invention it was found that cohesive strength of a gelinduced by ORC fibers is affected by supplementation with compounds asmeasured by a modified Bloom test.

Results of the modified bloom test demonstrate the force required by ametallic rod to pass through the gel at extension of 7 mm whilst movingat a speed of 5 mm/min. This force reflects the level of resistance ofthe gel (the greater the force, the greater the resistance of the gel)and in turn indicates what is the level of cohesive strength of a gel.Cohesive strength represents the strength by which molecules of acomposition are bound together. The more force required for the rod toproceed with its steady movement, the greater the resistance of the gelis.

It was also found that supplementation of ORC fibers with either 3% or6% calcium chloride (CaCl₂) increased the resistance force in a dosedependent manner.

The findings according to the invention showed that supplementation ofORC fibers with 3% ferric chloride (FeCl₃) had a significant positiveeffect on the resistance of the formed clots.

When comparing the efficacy of 3% CaCl₂ supplementation withcompositions having positive charges that were further supplemented witheither 3% PS; or 3% PS and 3% εACA; or 3% PS and 3% chitosan, theresults indicated that there was an improvement in the resistance forceof the further supplemented compositions. However it was found thatincluding 3% lysine (Lys), which is another compound having positivecharges in the composition, had a negative effect and decreased theresistance force obtained.

Without being bound by the mechanism, supplementing ORC fibers withspecific positively charged compounds (e.g. different cations e.g.divalent cations provided by CaCl₂, protamine salt e.g. protaminesulfate or positively charged polysaccharide e.g. chitosan and an omegaamino carboxylic acid e.g. εACA) may increase the cohesive strength of agel formed by the hemostatic powder composition.

It was also found that supplementation of ORC fibers with either 3%chitosan or 3% PS, further to 6% CaCl₂ supplementation, showed anincrease in the clots' resistance force.

Also, further supplementation of the 6% CaCl₂ ORC composition with 3%εACA decreased the resistance of the clots.

In addition, it was found that the improved resistance forcedemonstrated in clots formed by supplementation of 6% CaCl₂, wasabolished in clots formed by supplementation of 6% CaCl₂ mixture withLysine (Lys). Also, supplementation of 6% CaCl₂—ORC with Arginine (Arg)had the same negative effect.

It was found that superior results in cohesive strength were obtainedwith ORC supplemented with 5.0% CaCl₂, 2.5% PS and 2.5% εACA.

These surprising findings show that supplementing ORC fibers withspecific positive compounds and specific combinations and concentrationsthereof improves the cohesive strength properties of a gel.

Also, it was found that supplemented-ORC fibers (with 5.0% CaCl₂, 2.5%PS and 2.5% εACA, a combination that exhibited superior cohesivestrength) in the form of aggregates had superior hemostaticcapabilities. A positive contribution of calcium chloride to thehemostatic efficacy of the supplemented ORC aggregates was observed.

Aggregates of the ORC fibers, with or without supplementation withdifferent concentrations of compounds, were explored in vivo for theirhemostatic effect. The tested compound-supplemented aggregates includedfiber combinations of 10.0% (w/w of the final mixture weight) long ORCfibers and 77.5-80.0% fine ORC fibers. In each experiment, fine ORCaggregates (without any supplementation) served as a comparativecomposition to examine the hemostatic efficacy of the supplementation ofthe compounds to ORC fibers. Success rates of complete bleedingarrest/complete hemostasis were measured. In vivo results reaffirmedthat all three compounds (calcium chloride, PS and εACA) are necessaryfor improving the hemostatic efficacy of ORC fibers and that for both PSand εACA a superior supplementation range is 2.5% to 5.0% and forcalcium chloride 5.0% to 6.5% (a cation concentration range of1.363%-1.636% w/w).

The results showed that the supplemented ORC can be at least 1.5 timesmore efficient than an ORC comparative composition (37.5% completehemostasis rate for supplemented ORC vs. 25% complete hemostasis ratefor ORC alone). In one aspect of the invention, the compositioncomprises cellulose-based fibers that have a size distribution of D90 ofless than 350 μm, and D50 of less than 167 μm, the fibers are at aconcentration range of 83.5%-90.0% w/w of the entire composition and aresupplemented with the following compounds: an omega amino carboxylicacid at a concentration range of 2.5%-5.0% w/w of the entirecomposition; protamine salt at a concentration range of 2.5%-5.0% w/w ofthe entire composition; a divalent cation salt, the cation concentrationin the salt being 1.3%-1.8% w/w of the entire composition.

The composition can be in the form of a powder and/or aggregates.

Non limiting examples of Omega amino carboxylic acid includeω-carboxylic acid with variable chain lengths including but not limitedto 2-aminoacetic acid (glycine), 3-aminopropanoic acid, 4-amino butanoicacid, 5-aminopentanoic acid, 6-aminohexanoic acid 7-aminoheptanoic acid,8-amino octanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, andε aminocaproic acid.

In one embodiment of the invention, the omega amino carboxylic acid isepsilon amino caproic acid (εACA).

In one embodiment of the invention the protamine salt is protaminesulfate.

In one embodiment of the invention the divalent cation salt is providedby calcium chloride.

In one embodiment of the invention the concentration ranges of εACA,protamine sulfate, and calcium chloride are 2.5%-5.0%, 2.5%-5.0%,5.0%-6.5% w/w, respectively, and the remaining weight of the compositionis contributed by the cellulose-based fibers to a total weight of 100%w/w.

The hemostatic composition can further comprise an additive selectedfrom the group consisting of carboxymethyl cellulose, an anti-infectiveagent, another hemostasis promoting agent, gelatin, collagen, orcombinations thereof.

In some aspects of the invention, the hemostatic compositions furtherincludes carboxymethyl cellulose (CMC) or other polysaccharides,anti-infective agents, hemostasis promoting agents, gelatin, collagen,or combinations thereof.

In one embodiment of the invention, the compound comprises protaminesulfate, calcium ions, and ε-aminocaproic acid [5% CaCl₂, 2.5% PS and2.5% epsilon-aminocaproic acid (εACA)]. Non limiting examples ofcellulose-based fibers are ORC fibers, Cotton fibers, Rayon fibers, andViscose fibers.

In one aspect, the invention provides methods for making thecompositions of the invention. The compositions have beneficialhemostatic properties and may have wound healing, and other therapeuticproperties.

In one embodiment the method comprising the steps of: mixingcellulose-based fibers having a size distribution of D90 of less than350 μm, and D50 of less than 167 μm or of a size distribution of D90 ofless than 177 μm, and D50 of less than 95 μm, the fibers being at aconcentration range of 83.5%-90.0% w/w of the entire composition withthe following powder compounds:

i—an omega amino carboxylic acid at a concentration range of 2.5%-5.0%w/w of the entire composition;ii—protamine salt at a concentration range of 2.5%-5.0% w/w of theentire composition; andiii—a divalent cation, the cation concentration being 1.3-1.8% w/w ofthe entire composition.

In one embodiment, the fibers in the hemostatic compositions accordingto the present invention are made from oxidized cellulose-based fibermaterials and/or from pre-shredded oxidized cellulose-based materials.In another embodiment the fibers in the hemostatic compositionsaccording to the present invention are made from oxidized regeneratedcellulose-based fiber materials and/or from pre-shredded oxidizedregenerated cellulose-based materials.

The cellulose-based fiber starting material for making the hemostaticcomposition can include absorbable woven or knitted fabric or non-wovenmaterials comprising cellulose-based material, in particular oxidizedcellulose and the neutralized derivatives thereof. For example, thecellulose-based material may be carboxylic-oxidized or aldehyde-oxidizedcellulose. Oxidized regenerated polysaccharides including, but withoutlimitation, oxidized regenerated cellulose (ORC) may be used. Oxidizedregenerated cellulose is of advantage due to its higher degree ofuniformity versus cellulose that has not been regenerated. Regeneratedcellulose and a detailed description of how to make oxidized regeneratedcellulose are set forth in U.S. Pat. Nos. 3,364,200, 5,180,398 and4,626,253, the contents of each of which are hereby incorporated byreference as if set forth in its entirety.

Examples of cellulosic based materials that may be utilized to preparefibers of the composition include, but are not limited to, INTERCEED®absorbable adhesion barrier, SURGICEL® Original absorbable hemostat,SURGICEL® NU-KNIT® absorbable hemostat, SURGICEL® FIBRILLAR™ absorbablehemostat, SURGICEL® SNoW™ absorbable hemostat.

The cellulose-based material, e.g. cellulose-based fabric, can be milledto obtain fibers that have a size distribution of D90 of less than 350μm and of D50 of less than 167 μm. If desired, the milling step can berepeated to obtain a size distribution of D90 of less than 177 μm, andD50 of less than 95 μm.

In one embodiment, the fibers for making the hemostatic composition areprepared by milling a cellulosic source material; the milling step ispreceded by forming material pieces by slitting and cutting thecellulosic source material. In this embodiment the milling step is atwo-part process with the second part performed in an air classifierwherein the second part can be repeated three times. After a first pass(time) in the air classifier, the resulting “long fibers” have a sizedistribution of D90 of less than 350 μm and D50 of less than 167 μm.After 3 passes (3 times) in the air classifier the resulting fine ORCfibers have a size distribution of D90 of less than 177 μm and D50 ofless than 95 μm.

In one embodiment of the invention, the “fine or short” cellulose-basedfibers in the composition have a size distribution of D90 of less than177 μm, and D50 of less than 95 μm.

The cellulose-based material can be mixed or supplemented with thecompounds before, during and/or after the milling steps.

In one embodiment, the hemostatic powder compositions according to theinvention comprising the fibers and the compounds are further subjectedto steps of compaction, to form aggregates, optionally furthercomprising the steps of drying, milling/grounding and sieving.

The present invention also relates to hemostatic compositions in theform of aggregates e.g. including compounds and cellulose-based materialthat have been milled, optionally humidified, compacted, and dried.

In one embodiment, the invention relates to hemostatic composition inthe form of aggregates composed of a plurality of interconnectedindividual cellulose-based fibers and compounds according to theinvention that are in aggregate form and e.g. have a diameter along itslongest axis that is less than about 420 μm and greater than about 75μm.

In another aspect, the invention relates to a method of making aplurality of hemostatic aggregates composition comprising the steps of:compacting the hemostatic powder composition and forming aggregates.

In one embodiment of the invention, the method further comprises thesteps of: compacting the hemostatic composition; subjecting thecompacted composition to drying, milling; and sieving, thereby obtaininghemostatic aggregates.

Aggregates can be made by: optionally including a step of humidifyingthe hemostatic powder composition; compacting, e.g. by roller and/orslugging, the powder to form hemostatic aggregates; dehumidifying;milling; sieving the hemostatic aggregates; and optionally dosing theresulting hemostatic aggregates into storage containers or into deliverydevices.

Before compacting, the powder can be humidified to a water content levelof between 11.0% and 16.0% by weight. The powder can be roller compactedor slugging compacted and then subjected to pre-breaking,dehumidification, and subsequently followed by a step of final millingand possibly sieving.

In one embodiment, the powder is compacted at a roller pressure of atleast 130 bars. The powder can be compacted at a roller force of atleast 26 kN/cm.

The resulting aggregates are selected to a targeted hemostatic aggregatefraction, e.g. by sieving. The targeted aggregates may have dimensionsalong their longest axis of 75-500 μm such as 75-420 μm. The hemostaticaggregates, intended for dosing, may have moisture content e.g. whenmeasured by “loss on drying” method of less than about 5%, morepreferably less than 2%.

Powder compaction can be carried out using the powder according to theinvention and a manual hydraulic press (Specac Ltd. Atlas 15 tons modelGS15011) and a suitable evacuable pellet die. The pellet die can have adiameter of 10 mm (Specac Ltd. GS03100) to obtain a capsule. The capsulecan be released from the pellet die and broken to increase surface areafor the next drying step. Broken capsule can be dried in a vacuum oven(Cole-Parmer vacuum oven models 05017-05) at 37° C. for approximately 16hours to remove any excess humidity (and reach a humidity of less than5% w/w). The dried broken capsule can be ground/milled e.g. at 20,000rpm for 30 seconds using IKA® tube mill control 9737790. In a next step,the milled capsules can be vigorously sieved using an MRC (manufacturer)sieve shaker (model LS-200 at an intensity level 2) for 1 minute througha set of 2 sieves; e.g. one with a pore size of 420 μm and another witha pore size of 75 μm. The milled capsules remaining between the twosieves can be collected. In the collected granules/aggregates the fibersand compounds are homogenously distributed.

In one embodiment according to the invention, compositions in the formof aggregates are made directly from cellulose-based fabrics, without amilling step before compaction or without using powders according to theinvention as a starting material. For example, cellulose-based fabricsare subjected to compaction and then to drying, milling/grounding andsieving as described above. Supplementation with the compounds can becarried out before, during and/or after compaction.

In one embodiment, making a hemostatic aggregate composition comprisesthe steps of mixing 83.5%-90.0% w/w cellulose-based fibers; an omegaamino carboxylic acid at a concentration range of 2.5%-5.0% w/w of theentire composition; protamine salt at a concentration range of 2.5%-5.0%w/w of the entire composition; and a divalent cation, the cationconcentration being 1.3%-1.8% w/w with; and subjecting the mixture tocompaction; and optionally drying, milling, and sieving the mixture;thereby obtaining said aggregates.

One or more peptides having positive charges can be further added to thecompositions according to the invention. Non limiting examples of suchpeptides are: abaecin, apidaecins, prophenin, indolicidin, melittin,magainins, LL-37, Bovine lactoferricin, Human lactoferricin, CecropinA1, Buforin II, Thanatin, Polyphemusin 1, Magainin 2, Humanβ-defensin-2, Rabbit kidney defensin. Penetratin/Antenapedia, TAT,SynB1, SynB3, PTD-4, PTD-5, FHV Coat-(35-49), BMV Gag-(7-25), HTLV-IIRex-(4-16), D-Tat, R9-Tat Transportan, MAP, SBP, FBP, MPG, MPG(ΔNLS),Pep-1, Pep-2.

One or more polysaccharides having positive charges can be further addedto the compositions according to the invention. Non limiting examples ofpolysaccharides having positive charges are chitosan and cationic guargum.

Positive cations can be added, such as cations from FeCl₃.

In one embodiment manufacturing process starts with ORC material, suchas SURGICEL® Original absorbable hemostat, which is cut into 2.54-5.08cm (1-2 inch) wide sections before the material is fed into a blade thatcuts the fabric into smaller pieces. The cut ORC fabric pieces are thenground into ORC fine fibers by two consecutive milling processes (hammermilling and air classifier milling). In an alternative embodiment, thecut ORC fabric pieces are converted directly into fine fibers in a ballmill.

The resulting ORC fine fibers are then humidified to between about 11%w/w and about 16% w/w as measured by Ohaus halogen moisture analyzer andthen roller compacted into large aggregates. Prior to compacting,whether be it before or after milling, the fibers are supplemented withthe compounds of the inventions in the form of particles and in asuitable concentration.

The term “particles” relates to a substance that is composed ofdispersed solid materials.

The humidifying step could be omitted if a sufficient amount ofhygroscopic compound such as calcium chloride is mixed with the ORCfibers. Sufficient amount of hygroscopic compound is, for example, anamount that allows humidification to a level of between about 11% andabout 16% as measured by Ohaus halogen moisture analyzer.

The term “hygroscopic material” relates to a substance that is capableof attracting and holding water molecules from the surrounding, usuallyat normal or room temperature environment. Non limiting examples includezinc chloride, calcium chloride, potassium hydroxide and sodiumhydroxide.

The moisture analyzer operates on a thermogravimetric principle whereinthe moisture analyzer determines the weight of the sample; the sample isthen quickly heated by the integral halogen dryer unit and moisturevaporizes. During the drying operation, the instrument continuouslydetermines the weight of the sample and displays the result. Uponcompletion of drying, a tabulated result is displayed as percentmoisture content, percent solids, weight or percent regain, inparticular, the analyzer tests between 0.5 gr-1.0 gr of aggregates witha 4 minute ramp, 90° C. maximum temperature and the following settings:Test ID—LOD; Profile—Standard; Dry Temperature—90° C.; Switch Off—A60;Result—Moisture %; Custom—Off; Target Weight—None.

Typically, sieving is carried out to separate target aggregates/granulesbetween the size of 75 μm and 420 μm as determined by screen sieving.

In one embodiment, excess moisture introduced for purposes of compactionis removed by a dehumidification or drying process. After compaction,milling and sieving steps, the composition is dosed into applicatordevices. Then the composition in the device is subjected to packagingand sterilization.

In one embodiment, storage moisture prior to dosing into an applicatoris less than about 2% at conclusion of drying to achieve preferably lessthan 6% moisture content in controlled environment (0.3-0.6%/hr per 500gram sample moisture gain depending on relative humidity, commonly25-55% relative humidity) for dosing into applicators.

One process for manufacturing the hemostatic aggregates comprises, forexample, the steps of:

(a) providing a cellulose-based (cellulose source) material andoptionally, slitting and cutting the cellulose-based material;Optionally, (b) reducing the size (e.g. by milling in an air classifier)of the material from step a) to obtain long fibers;(c) reducing the size (e.g. by milling in an air classifier) of thematerial from step a) or b) to obtain fine fibers;optionally, (d) mixing long and fine fibers to obtain mixed fibers;(e) supplementing the fibers from step c) or d) with the compounds toobtain compound-supplemented fibers;optionally, (f) humidifying the compound-supplemented fibers obtained instep e) to obtain compound-supplemented humidified fibers;(g) compacting the compound-supplemented humidified fibers of step f)(e.g. by slugging or rolling) including dehumidification/drying andoptionally, reducing size;(h) sieving;optionally, (i) dosing into storage containers or into delivery devices,primary packaging and secondary packaging; andoptionally, (j) sterilizing.

In one embodiment, the humidifying step could be omitted if a sufficientamount of a hygroscopic compound such as calcium chloride is added tothe fibers.

Slitting and cutting can preferably be performed to slit and cut fabricinto appropriate size pieces that are between approximately 2.54 cm by7.62 cm or 5.08 cm by 7.62 cm (1 inch by 3 inches or 2 inches by 3inches), though smaller pieces can also be used. The main operationsperformed for slitting and cutting are to unwind a roll of fabric, slitthe fabric into strips, cut the strips to size and deliver the cutpieces into the first milling step. A number of cutting and slittingmachines are known and commercially available, such as AZCO ModelFTW-1000 available from AZCO. Supplementation with the components can becarried out before or after slitting and cutting the fabric.

In one embodiment, in the first milling step, processed pieces ofcellulose fabric are converted from a coarse fiber produced in theslitting and cutting step to a material having a D90 value of less than452 μm and D50 value of less than 218 μm, while having minimal impact onthe color index and water soluble content of the material. A number ofmachines for milling are commercially available, such as Models DASO6and WJ-RS-D6A manufactured by Fitzpatrick, which are hammer mill typemilling machines, equipped with a 497 μm round screen and a set ofblades that break down the fabric until it passes through the screen toproduce coarse cellulose fibers. In an exemplary processing run, millspeed can be about 7000 RPM; processing temperature at less than 80° C.;number of blades as 8 (2 impellers each); blade type as a 225 knife,impact type blades; blade orientation set as “impact”.

At this stage, the size of the coarse fiber produced in the firstmilling step can be further reduced to a D90 value of less than 177 μmand a D50 value of less than 95 μm while keeping minimal impact on thecolor index and water soluble content of the material. A number ofmachines are available for the second milling step, such as an AirClassifier/F10 Quadro Fine Grind from Quadro.

Coarse fiber from the first milling step can be fed at a controlled rateinto the second mill and passed through two milling chambers that areseparated by a milling screen. The material can be pulled through themilling chamber by an air blower. The coarse fiber can be processedthrough the air classifier equipment three times in order to obtain afine fiber size. At the end of the second milling step, the fine fiberscan be collected.

In an exemplary processing run, a Quadro Air Classifier F10 can be usedin the second milling step with a milling speed of 8400 rpm, blowerspeed of 1800 rpm and 3 passes. ORC fine fiber can also be produced inone step by ball milling instead of the two milling steps as describedabove. In an alternative ball milling embodiment, 50 g of pre-cut ORCfabric, pieces of about 5.08 cm by 5.08 cm (2 inch×2 inch), is ballmilled with 12 high-density Zirconia (zirconium dioxide ZrO2, 20 mm indiameter; Glen Mills Inc., Clifton, N.J., USA) by placing the balls andthe samples in a 500 mL grinding jar. The jar is clamped into thelatching brackets and then counterbalanced on the planetary ball millPM100; Retsch, Inc., Newtown, Pa., USA). The milling is then performedbi-directionally at 450 rpm for 20 minutes.

Following the milling process, the resulting cellulose-based fine fiberscan be humidified to moisture content in the range of about 11% to about18%, or between about 11% and about 16%, or about 12-16% for thesubsequent processing, including e.g. a roller compaction process.Humidity chambers suitable for the humidification step are commerciallyavailable e.g. Model CEO-916-4-B-WF4-QS by Thermal Product Solutions.Humidification of chamber air is achieved by water vapor injection. Thetypical steady-state temperature of 25° C. can be utilized, while thehumidity level can be cycled between 75% and 85%, with a preferredtarget of 85% air humidity. Humidification time or residence time of thematerial inside the humidity chamber can range from several hours toseveral days depending on the quantity of the material and airrecirculation. In a typical cycle, the material will have 12-13 hoursresidence time for about 3,000 grams of cellulose-based fine fibersarranged in several trays and exposed to 85% relative humidity and atarget of 12% moisture content of the powder after humidification.

The roller compactor compacts the feed of humidified fine ORC fibers,which are then subjected to pre-breaking, dehumidification, finalmilling and sieving in a screener to obtain the desired hemostaticaggregates sizes.

Typically, supplementation with compounds according to the invention iscarried out before compaction and/or before aggregates are produced.

Compaction equipment is known and commercially available. Fibers couldbe compacted by slugging machinery or any other compaction techniqueknown in the art. Exemplary compaction units are the FitzpatrickChilsonator IRR220-L1A with Retsch manual sieving AS200 Screener and theFitzpatrick Chilsonator CCS220/M3B & RV-M5A with Screener SwecoVibro-energy unit integrated under M5A. The compaction processing can beperformed using two separate subsystems that are bound by a commonelectrical system. For example, a first subsystem (Roller Compactor:main unit) can be the Fitzpatrick Chilsonator CCS220 roller compactorand the M3B mill for pre-breaking the compacted material, while thesecond subsystem (Roller Compactor: secondary milling unit) is M5A millfor the final milling with a Sweco or Retch screener for the separationto obtain the desired size aggregates.

Humidified fine cellulose-based fibers can be fed into the hopper of theroller compactor unit, first passed through a main milling unit and thenproceed on through a second milling unit. A container can be providedthat captures the pre-broken cellulose-based material resulting from themain milling unit. The pre-broken pieces of cellulose-based material canthen be fed into the secondary milling unit, which performs the finalmilling and screening utilizing a screen mesh. The resulting milledcellulose-based material is preferably separated into “fines” (<75 μm),“targets” (75-420 μm), and “overs” (>420 μm) using a screen mesh, suchas the Sweco or Retch screener described above.

Moisture is removed from hemostatic aggregates that are obtainedfollowing compaction and sieving in a dehumidification or drying step.The dehumidification or drying step preferably does not significantlyaffect any other product quality attributes, such as color, bulk densityand size. Typically, the fibers can be dried as a batch using aconventional fluidized air bed. The resulting dried aggregates can bepacked and stored in sealed foil pouches. Dehumidification equipment isknown and commercially available. An exemplary bench-top fluidized airbed is commercially available from Retsch (TG-200) with 6 L capacity.Alternatively, a fluidized bed Model No. 0002 from Fluid Air (Aurora,Ill.) can also be used.

In further aspects of the present invention, the hemostatic compositionsin the form of powder and/or aggregates can be combined with variousadditives to further improve the hemostatic properties, wound healingproperties, and handling properties, including: hemostatic additives,such as gelatin, collagen, cellulose, chitosan, polysaccharides, starch,CMC; biologics based hemostatic agents such as thrombin, fibrinogen, andfibrin, additional biologics hemostatic agents include, withoutlimitation, procoagulant enzymes, proteins and peptides, each such agentcan be naturally occurring, recombinant, or synthetic, and may befurther selected from the group consisting of fibronectin, heparinase,Factor X/Xa, Factor VII/VIIa, Factor IX/IXa, Factor XI/XIa, FactorXII/XIIa, tissue factor, batroxobin, ancrod, ecarin, von WillebrandFactor, albumin, platelet surface glycoproteins, vasopressin andvasopressin analogs, epinephrine, selectin, procoagulant venom,plasminogen activator inhibitor, platelet activating agents, syntheticpeptides having hemostatic activity; anti-infective agents, such aschlorhexidine gluconate (CHG), triclosan, silver, and similaranti-bacterial/microbial agents that are known in the art; additivesthat increase the stickiness of the hemostat; diluents, salinesolutions, similar additives known in the art; derivatives of the aboveand any combination thereof.

In one embodiment, hemostatic powder and/or aggregates compositionaccording to the present invention are made from oxidizedcellulose-based fiber materials such as ORC or from pre-shreddedoxidized cellulose-based materials.

In one embodiment of the invention, the powder composition has theproperty of forming a gel upon contact with blood. The formed gel has aresistance of equal to or higher than 10 times that of a gel formed uponcontact of a comparative composition with blood.

In one embodiment a comparative powder composition consists of OxidizedRegenerated Cellulose (ORC) alone.

The term “gel” relates to a viscous and/or solid-like material that canhave properties ranging from soft and weak to hard and tough. The gelcan be a hydrogel.

Typically, a hydrogel is a network of polymer chains that arehydrophilic. Hydrogels can contain over 90% water and include polymericnetworks.

The gel can be a clot being a thick mass of coagulated liquid,especially blood.

The term “contacting/contact” is used in its broadest sense and refers,for example, to any type of combining action which brings the hemostaticcomposition into sufficiently close proximity with the blood such that aclot or gel is formed.

The term “blood” includes blood fractions such as plasma.

In one embodiment, the comparative powder composition is composed of ORCfibers having a D90 value of less than 350 μm and a D50 value of lessthan 167 μm.

In one embodiment of the invention, the aggregates and/or powdercomposition according to the invention has the property of forming a gelupon contact with blood. The formed gel has a hemostatic capability ofequal to or higher than 1.5 times that of a gel formed upon contact of acomparative aggregates composition with blood.

In one embodiment, the comparative aggregates composition is composed,for example, of ORC fibers having a D90 value of less than 350 μm and aD50 value of less than 167 μm.

In one embodiment, the comparative aggregates is composed, for example,of ORC fibers having a D90 value of less than 177 μm and a D50 value ofless than 95 μm.

The term “resistance of a gel” relates to the results of the modifiedbloom test (as exemplified below) that demonstrate the force required bythe metallic rod to pass through the gel at extension of 7 mm whilstmoving at a speed of 5 mm/min. This force reflects the level ofresistance of the gel (the greater the force, the higher the resistanceof the gel) and in turn indicates what is the level of cohesive strengthof a gel. The greater the force required for the rod to precede with itssteady movement, the greater the resistance of the gel.

In a further aspect, the invention provides a method for forming a gelcomprising the step of:

contacting a hemostatic composition according to the invention withblood, thereby forming a gel.

In one embodiment, the method forms a gel having a resistance of equalto or more than 10 times or more than 12 times higher than that of a gelformed upon contact of a comparative composition with blood, and/orforms a gel having a hemostatic capability of equal to or more than 1.5times higher than that of a gel formed upon contact of a comparativecomposition with blood.

In one embodiment, the comparative composition comprises cellulose-basedfibers and lacks omega amino carboxylic acid at a concentration range of2.5%-5.0% w/w of the entire composition; lacks protamine salt at aconcentration range of 2.5%-5.0% w/w of the entire composition; andlacks a divalent cation, the cation concentration being 1.36-1.77% w/wof the entire composition.

In a further aspect, the invention provides a kit comprising a containerincluding a hemostatic composition of the invention, and optionally anapplicator, a carrier, and/or instructions for use. The term “carrier”relates to a physical matrix comprising and/or holding the hemostaticcomposition. Examples of carriers include, but are not limited to, padsfor internal and/or external use such as cellulose-based pads,collagen-based pads; implants such as orthodontic and orthopedicimplant; flowable sealants and/or hemostats such as SURGIFOAM®, EVICEL®.

In some embodiments, the container is an applicator.

In one embodiment, aggregate or powder composition with 5.0% CaCl₂, 2.5%PS and 2.5% εACA is equivalent to: 40 mg/cm² CaCl₂ 20 mg/cm² PS, 20mg/cm²εACA.

For example, if a total amount of 100 mg final composition is applied ona circular punch having a diameter of 0.4 cm. The 100 mg composition wasapplied on the punch surface area which is π*(0.2 cm)²=0.126 cm².Meaning that 793.65 mg/cm² (resulting from the calculation: 100 mg/0.126cm²) of final composition was used.

If CaCl₂ is used at a concentration of 5% of the final composition,therefore 793.65*0.05 equals to about 40 mg/cm².

If PS is used at a concentration of 2.5% of the final composition,therefore 793.65*0.025 equals to about 20 mg/cm².

If εACA is used at a concentration of 2.5% of the final composition,therefore 793.65*0.025 equals to about 20 mg/cm².

The hemostatic composition may have one or more of the followingadvantages over several known products:

1—can stop bleedings e.g. at large blood vessels suture line andtherefore can significantly reduce and stop bleeding from blood vesselssuture lines unlike several known products which have limited efficacyin achieving hemostasis in blood vessels;2—can achieve hemostasis without the need for pressure application.Several known products require the application of pressure in order toachieve hemostasis (e.g. manually compressing with a gauze);3—is activated in blood. When activated by moisture, the hemostaticfibers and/or aggregates gain structure (e.g. in the form of a clot/gel)and can achieve hemostasis. Several known products have pre-formedstructural integrity;4—can set in blood, does not float away easily and can achieveshemostasis. Several known products have limited efficacy in a wetenvironment;5—can adhere to the bleeding site, yet still reversible i.e. adheres tothe bleeding site and resists lavage, yet can be scraped off to removeand gain access if surgical correction is needed. Several known productshave either limited adherence in a wet field or they cannot be easilyremoved once applied.

The hemostatic compositions can be used for various surgical and woundhealing topical applications, such as anti-adhesion barriers, hemostats,tissue sealants, etc. The hemostatic compositions of the presentinvention can perform as a hemostat, as dry composition or as acomposition in a paste form with superior hemostatic properties and goodtissue conformability.

The hemostatic fibers and/or aggregates composition can be used forvarious surgical and/or wound healing topical applications, such as foranti-bactericidal treatment, hemostasis, anti-adhesion, sealing, and/orfor minimizing or preventing leaks e.g. leaks from anastomotic sitessuch as leaks created during coronary artery bypass graft (CABG).

The composition may be used to stop bleeding in hard to reach areas e.g.during laproscopic surgery, on anastomotic sites such as CABG and/orarteriovenous anastomosis, procedures where applying pressure isunwarranted such as spinal surgery or neuronal surgery.

Patients that undergo coronary artery bypass graft (CABG) surgery mayhave leaks from the anastomotic sites created during the procedure. Manyof these leaks are addressed during the surgery using either additionalsutures or various hemostats. Stopping these leaks during surgery andpreventing them from developing post operatively, will help surgeons bemore confident that their patients will not have post-operativeanastomotic leaks. Bleeding after CABG procedures requiring atransfusion or reoperation is associated with a significant increase inmorbidity and mortality. In as many as 20% of cases, a specific site ofbleeding can be identified, during the reoperation. The typical sourcesof surgical bleeding include cannulation sites, the proximal and distalanastomotic site, and the branches of the ITAs and vein grafts.According to literature, 2-3% of CABG patients will requirere-exploration for bleeding and as many as 20% will have excessivepost-operative bleeding requiring blood transfusion.

The content of all cited publications are hereby incorporated byreference in their entirety.

Examples

Materials and Methods.

TABLE 1A Oxidized Regenerated Cellulose (ORC) Fibers. OxidizedRegenerated Cellulose (ORC) Fibers Category Long ORC FibersDistribution: D90 of less than 350 μm and D50 Cellulose-based of lessthan 167 μm* fibers Fine ORC Fibers Distribution: D90 of less than 177μm, and D50 Cellulose-based of less than 95 μm* fibers *See belowelaboration on the preparation.

TABLE 1B Compounds used to supplement ORC Fibers. Compound CategoryManufacturer Cat. Number Calcium Chloride Divalent cation Merck1.42000.5000 dehydrate (CaCl₂) salt Protamine Protamine salt SigmaP3369-100G Sulfate (PS) 6-Aminocaproic Omega amino Sigma A204-100G acid(ε- carboxylic acid aminocaproic acid = epsilon- aminocaproic acid =εACA) Chitosan Positively charged Sigma 448869-50G polysaccharide FeCl₃Trivalent cation Sigma 157740 Lysine Positively charged Sigma L5501amino acid

TABLE 2 % (w/w) of cation concentration equivalent in CaCl₂ and FeCl₃.Amount of Amount of calcium Amount of Ferric indicated salt cationscations (w/w) (w/w) (w/w) 3.0% CaCl₂ 0.818% — 3.5% CaCl₂ 0.954% — 5.0%CaCl₂ 1.363% — 6.0% CaCl₂ 1.636% — 6.5% CaCl₂ 1.768% — 3.0% FeCl₃ —1.033%

Oxidized Regenerated Cellulose (ORC) Fibers Preparation:

The manufacturing process of the ORC fibers started with ORC materialSURGICEL® Original absorbable hemostat. ORC material was cut into2.54-5.08 cm (1- to 2-inch) wide sections before the material was fedinto a blade that cuts the fabric into smaller pieces. The cut ORCfabric pieces were then ground into ORC fine fibers by two consecutivemilling processes (hammer milling and air classifier milling). Thefibers from different milling steps were taken for future use in orderto incorporate different fiber sizes in the final aggregates.

More specifically, the process for manufacturing the fibers comprisedthe steps of: slitting and cutting of SURGICEL® Original fabric; millingthe resulting material using hammer milling; milling step(s) in an airclassifier for obtaining long and fine fibers; and optionally mixingfibers of the different sizes. Different fiber sizes are fibers havingdifferent size distribution.

Slitting and cutting was carried out to slit and cut fabric intoappropriate size pieces that are approximately 2.54 cm by 7.62 cm (1inch by 3 inches). The main operations performed for slitting andcutting were to unwind a roll of fabric, slit the fabric into strips,cut the strips to size and deliver the cut pieces into the first millingstep.

In a first milling step, processed pieces of cellulose-based fabricmaterial were converted from an intermediate coarse fiber produced inthe slitting and cutting step to a material having a D90 value of lessthan 452 μm and D50 value of less than 218 μm, while having minimalimpact on the color index and water soluble content of the material. Themachine used for milling at this step was a hammer mill type modelWJ-RS-D6A manufactured by Fitzpatrick. The hammer mill was equipped witha 497 μm round screen and a set of blades that breaks down the fabricuntil it passes through the screen to produce intermediate coarsecellulose-based fibers. The parameters of the milling were: mill speedof about 7000 RPM; processing temperature of less than 80° C.; number ofblades of 8 (2 impellers each); blade type of a 225 knife, impact typeblades; blade orientation set as “impact”.

Intermediate coarse fibers from the first milling step were fed at acontrolled rate into the second mill. The intermediate coarse fiberswere processed through the air classifier equipment three times in orderto obtain the desired size. In addition, in certain experiments, fiberstaken from the first run through the air classifier were extracted inorder to incorporate different fiber sizes in the final aggregates.

At this step(s), a Quadro Air Classifier F10 was used with a millingspeed of 8400 rpm, blower speed of 1800 rpm and 3 passes. After onepass, the resulting long ORC fibers had a D90 value of less than 350 μmand a D50 value of less than 167 μm. After 3 passes, the resulting fineORC fibers had a D90 value of less than 177 μm and a D50 value of lessthan 95 μm.

Powder Composition Preparation.

All powders were weighed using an analytical balance in humiditycontrolled conditions. Relative humidity did not exceed 20% throughoutthe powder preparation process. All powders were comprised of ORC fibershaving D90 of less than 350 μm and D50 of less than 167 μm, prepared asdescribed above, and supplemented with different positively chargedcompound(s). A positively charged compound is a material containing apositively charged group/element within it. In examples 1-3 the ORCfibers of the powder or aggregates composition included fine ORC fibers;For example, if the compound was 3% FeCl₃ (w/w from the entirecomposition weight), the ORC fine fibers constituted 97% w/w. (see sizedistribution in table 1A); in example 4, the ORC fibers of thesupplemented aggregates were a combination of 10.0% (w/w of the finalmixture weight) long ORC fibers (see size distribution in table 1A) and77.5-80.0% (w/w of the final mixture weight) fine ORC fibers. Thesupplementation of compound(s) to ORC fibers was up to 10.0% (w/w) inthe in-vitro testing and up to 12.5% (w/w) in the in-vivo testing. Allcompounds, elaborated in the Table 1B, were provided in powder form.

Each fibers-compound(s) mixture combination was transferred to a mortarand pestle and mixed thoroughly until the powder particles wereequally/homogenously distributed within the composition. To minimizeadsorption of humidity, the powder compositions were stored in vials andsealed with a plastic paraffin film (PARAFILM®).

The compositions in Examples 1-2 were in powder form. In Example 3, thenon-compacted composition was in powder form while the compactedcompositions were in aggregate form. In Example 4, all compositions werein aggregate form (see elaboration on aggregate preparation below).

Aggregate Preparation.

To obtain aggregates/granules that contain a higher mass per volumeratio, two steps were carried out:

-   -   I—Powder compaction (capsulation); and    -   II—Capsule drying, milling/grounding and sieving.

See elaboration of steps I and II below.

Powder Compaction.

Compaction was carried out using a manual hydraulic press (Specac Atlas15 tons model GS15011) and a suitable evacuable pellet die, the pelletdie has a diameter of 10 mm (Specac GS03100). About 300 mg powdercomposition (prepared as described above) was loaded into the pellet dieup to a height of approximately 1.5 cm-2.0 cm. In the next step, ametallic rod (which is part of the manual hydraulic press equipment) wasfitted on top of the powder and used to reach a pressure of 4 tons(about 1.3 tons per cm²) by the manual hydraulic press. Following thisstep, a capsule (compacted powder) in a diameter of 10 mm and a heightof approximately 0.3 cm-0.5 cm was formed. The capsule was released fromthe pellet die and broken into smaller parts with a mortar and pestle toincrease surface area for the next drying step.

Capsule Drying, Milling/Grounding and Sieving.

Capsule halves were dried in a vacuum oven (Cole Parmer vacuum ovenmodel 05017-05) at 37° C. for approximately 16 hours to remove anyexcess humidity (and reach a humidity of less than 5% w/w). The driedcapsule parts were ground/milled at 20,000 rpm for 30 seconds using IKA®Works, Inc. tube mill control 9737790. In the next step, the aggregateswere vigorously sieved using an MRC (sieve manufacturer) sieve shaker(model LS-200 at intensity level 2) for 1 minute through a set of 2sieves; one with a pore size of 420 μm and another with a pore size of75 μm. The aggregates remaining between the two sieves were collectedand stored at room temperature (20° C.-27° C.) in a tightly closed vial,sealed with plastic paraffin film until use. At the end of this stage,all the components present in each final granule/aggregate compositionwere homogenously distributed within it.

Blood Preparation.

Blood used in Examples 1-2 was collected from exterminated Porcines byLahav contract research organization (C.R.O.) and delivered in chilledcontainers (4° C.). Upon blood collection, 5000 IU Heparin was added perliter of blood [Heparin Sodium-Fresenius 5000 IU/1 ml solution forinjection; manufacturer: BODENE (PTY) LTD trading as Intramed; Cat.Number: 9207910LAB].

To prevent clotting, upon arrival additional Heparin was added (5000 IUper 1 liter blood). The heparinized blood was mixed gently by invertingthe bottle several times. In the next step, to remove residual clots,the heparinized blood was filtered through a 20 μm polypropylene syringefilter (SVL25D20HQSA25 by Entegris) and collected into a polypropylenecontainer (to prevent blood clotting induced by glass). The filteredheparinized blood was stored at 4° C. until use.

Bloom Test.

Bloom is a test used to measure the cohesive strength of a gel orgelatin. Cohesive strength represents the bonding between the moleculesof a tested material/composition. Generally, Bloom test relates todetermination of the force (in grams) which has to be applied to a freesurface of 6.67% gelatin gel (prepared by dissolving 7.5 gr gelatin in105 gr water) by means of a cylindrical piston (having a diameter of12.7 mm) in order to produce a depression of 4 mm. For the test, the gelis typically formed in a glassware with the following dimensions: acapacity of 150 ml, an interior diameter of 59 mm, and a height of 85mm. The speed of the descending piston is set to 30 mm/minute (see Bloomtest described in U.S. Pat. No. 1,540,979).

In the Examples below, a modified Bloom test was carried out to test thecohesive strength of clots formed when different tested powdercompositions were mixed with blood. This parameter was assessed as anindication of the potential hemostatic efficacy of each testedcomposition. Generally, a higher resistance force (a high value in theBloom test) correlates with higher cohesive strength and suggests thatthe composition has a high hemostatic efficacy; low resistance forcecorrelates with low cohesive strength and suggests that the compositionhas low hemostatic efficacy. The cohesive strength induced by eachtested powder composition was evaluated on a comparative basis to thenon-supplemented ORC fibers. The results are presented as fold increasein the resistance force relative to the non-supplemented ORC fibers.

The modified Bloom test was carried out as follows:

-   -   1) 300 mg of each tested powder composition was weighed into a 7        ml tube (interior diameter: 15 mm, height: 50 mm).    -   2) 2.5 ml of blood (prepared as described above under “Blood        preparation”) was added to each powder composition.    -   3) The tube was vortexed vigorously at 3200 rpm until no dry        powder was visually apparent and the blood-powder composition        mixture was incubated for 3 minutes to enable clot formation.    -   4) To measure the cohesive strength, the vial was placed in a        ‘Lloyd LF plus’ instrument and a metallic rod [1.27 cm (0.5        inch)] was inserted into the vial at a constant pre-set        descending speed: 5 mm/minute. The resistance force of the clot        to the movement of the metallic rod at the point of 7 mm        extension into the clot was measured in units of megapascal        (MPa). The test was carried out at room temperature.

Suture Pre-Clinical Model.

A pulsatile ex-vivo cardiopulmonary bypass (CPB) model was used tosimulate physiological conditions. The model is described in:

-   Sergeant, P., Kocharian, R., Patel, B., Pfefferkorn, M., &    Matonick, J. (2016). Needle-to-suture ratio, as well as suture    material, impacts needle-hole bleeding in vascular anastomoses.    Interactive CardioVascular and Thoracic Surgery, 22(6), 813-816.    doi:10.1093/icvts/ivw042.

Briefly, the pulsatile ex vivo cardiopulmonary bypass model used aseries of pumps and chambers to create, control and maintain bloodpressure throughout the system. The model consists of a reservoir tofilter blood going into and returning from a porcine carotid artery, acomputer-integrated data acquisition system, oxygenator and heatexchanger. Flow impedance and volume partitioning adjustments arepresent to allow for fine adjustment of blood volume flow and pressurecontrol.

The blood loss from the suture placed in the porcine carotid artery wascollected and weighed to establish a leak rate. The leak rate wascalculated and recorded as the volume of blood collected over a periodof time.

To simulate physiological conditions, the following parameters wereused:

Pressure of 120/80 mmHg

Pulse rate of 72/min

Blood temperature of 33-35° C.

10,000 IU of heparin were added to 1 L of donor porcine blood andtitrated with 10 mg/ml Protamine sulfate to adjust activated clottingtime (ACT) to approximately 369 seconds. ACT was measured with a VetScani-STAT Portable Handheld Unit (Abbott Point of Care) and an I-STAT ACTCelite Cartridge (Abbott Poing of Care, Part#:600-9006-10).

A porcine carotid artery was isolated from the surrounding tissue andmounted on the system. Tubing clamps were used to secure the tissue tothe fittings. Blood flow on both sides of the carotid was restricted andthe carotid was sutured in a simple continuous pattern with a 6-0PROLENE Suture (8806H) and a BV-1 needle. Blood loss mass over 2 minuteswas measured as a baseline.

The powder/aggregates were applied over the sutured sites and allowed tocure for 4 minutes following complete application. Restriction wasremoved and the blood loss mass over 2 minutes was measured.

Liver Biopsy Punch In-Vivo Model.

A mature, about 60 kg, female porcine was put on a fast for 24 hoursprior to the surgical procedure. The animal was anesthetized with 1150mg-1400 mg Ketamine, 115 mg-140 mg Xylazine, 7.5 mg Midazolam.Anesthesia was maintained with Isoflurane and the abdomen was opened toreveal the liver. Mean arterial blood pressure, body temperature andheart rate were continuously monitored throughout the surgicalprocedure. The experiment was terminated when mean arterial bloodpressure dropped below 60 mmHg.

A 4 mm diameter×2 mm depth biopsy punch was carried out on the liverlobe and the specimen was excised with surgical scissors. The punch sitewas allowed to bleed for 30 seconds and bleeding intensity was visuallyassessed on a scale of 0-5; whereby no bleeding was given a score of 0and intensive bleeding was given a score of 5. Then, the punch site waswiped with clean gauze to remove excess blood and 100 mg of the testedaggregate composition was poured into the punch cavity (for example, anaggregate composition with 5.0% CaCl₂, 2.5% PS and 2.5% εACA isequivalent to: 40 mg/cm² CaCl₂, 20 mg/cm² PS, 20 mg/cm²εACA).

A total amount of 100 mg final composition is applied on a circularpunch having a diameter of 0.4 cm. Therefore, the 100 mg composition wasapplied on the punch surface area which is π*(0.2 cm)² about 0.126 cm².Meaning that 793.65 mg/cm² (resulting from the calculation: 100 mg/0.126cm²) of final composition was used.

CaCl₂ is used at a concentration of 5% of the final composition,therefore 793.65*0.05 equals to about 40 mg/cm².

PS is used at a concentration of 2.5% of the final composition,therefore 793.65*0.025 equals to about 20 mg/cm².

εACA is used at a concentration of 2.5% of the final composition,therefore 793.65*0.025 equals to about 20 mg/cm².

Mild pressure was manually applied over the composition using cleangauze for 1 minute. Bleeding was monitored over a period of 4 minutes,after which bleeding intensity was rated again on a scale of 0-5. Theresults are presented as percentage of complete hemostasis rate achievedfrom all replicates.

Example 1: The Effect of Different Compounds on the Cohesive Strength ofa Clot Formed with Fine ORC Fibers

The purpose of this Example was to examine the cohesive strength inducedby ORC fibers supplemented with different compounds. For this purpose, amodified Bloom test was carried out as described above.

The tested powder compositions comprised of fine ORC fibers supplementedwith different compounds as shown in FIG. 1. The powders were preparedas described in the Materials and Methods section under “PowderPreparation”. Table 2 above shows the percentage (w/w based on theentire weight composition) of cations in CaCl₂ and FeCl₃ used in all theexperiments below. FIG. 1 is a bar graph showing the fold increase ofthe resistance force/cohesive strength obtained for the different testedpowder compositions as compared to non-supplemented fine ORC fibers.

Results of the modified bloom test demonstrate the force required by themetallic rod to pass through the gel, formed with the tested compositionupon contact with blood, at extension of 7 mm whilst moving at a speedof 5 mm/min. This force reflects the level of resistance of the gel (thegreater the force, the greater the resistance of the gel) and in turnindicates what is the level of cohesive strength of a gel. Cohesivestrength represents the strength by which molecules of a composition arebound together. The more force required for the rod to proceed with itssteady movement, the greater the resistance of the gel is.

The results show that supplementation of fine ORC fibers with 3% FerricChloride (FeCl₃) had a significant positive effect on the resistance ofthe formed clots.

It was also shown that supplementation of fine ORC fibers with either 3%or 6% calcium chloride (CaCl₂) increased the resistance force in a dosedependent manner.

When comparing the efficacy of 3% CaCl₂ supplementation withcompositions that were further supplemented with either 3% PS; or 3% PSand 3% εACA; or 3% PS and 3% chitosan, the results indicated that therewas an improvement in the resistance force of the further supplementedcompositions. Including 3% lysine (Lys) in the composition had anegative effect and decreased the resistance force obtained (comparefine ORC fibers supplemented with 3% CaCl₂ and 3% PS vs. fine ORC fiberssupplemented with 3% CaCl₂, 3% PS and 3% Lys in FIG. 1).

It can be concluded that adding specific positively charged compound(s)such as calcium chloride, protamine sulfate (PS) and/or chitosan to ORCfibers improves the cohesive strength induced by the fibers, suggestingthat these supplemented composition may have a beneficial hemostaticeffect in-vivo.

Without being bound by the mechanism, supplementing ORC fibers withspecific positively charged compounds (e.g. different cations e.g.divalent cations provided by CaCl₂, protamine salt e.g. protaminesulfate or positively charged polysaccharide e.g. chitosan and an omegaamino carboxylic acid e.g. εACA) increases the cohesive strength of agel formed by the hemostatic powder composition.

Example 2: The Effect of Supplementation Combinations on the CohesiveStrength Induced by a Powder Composition

The previous Example indicated that supplementation of fine ORC fiberswith 6% CaCl₂ resulted in a higher resistance force/cohesive strength ascompared to 3% CaCl₂. The previous Example showed that furthersupplementation of 3% CaCl₂-fine ORC fibers composition with additionalpositively charged compounds increased the cohesive strength of thecomposition. Therefore, in this Example the contribution of furthersupplementation of a composition of fine ORC fibers with high CaCl₂concentrations (5% or 6%) with additional positively charged compounds,to the cohesive strength was tested. The results are shown in FIG. 2.

Similar to the results shown in the previous Example, supplementation of6% CaCl₂—ORC mixture resulted in an increase in resistanceforce/cohesive strength as compared to ORC only. It was found that theimproved resistance force demonstrated in clots formed bysupplementation of 6% CaCl₂, was abolished in clots formed bysupplementation of 6% CaCl₂ mixture with Lysine (Lys). Additionalsupplementation of 6% CaCl₂—ORC with Arginine (Arg) had the samenegative effect.

Supplementation of ORC fibers with either 3% chitosan or 3% protaminesulfate (PS), further to 6% CaCl₂, demonstrated an increase in theclots' resistance force.

Furthermore, further supplementation of the 6% CaCl₂ ORC compositionwith 3% εACA alone decreased the resistance of the clots (compare fineORC fibers supplemented with 6% CaCl₂ vs. fine ORC fibers supplementedwith 6% CaCl₂ and 3% εACA in FIG. 2).

Superior results were obtained with ORC supplemented with 5.0% CaCl₂,2.5% PS and 2.5% ε-aminocaproic acid (εACA).

These results suggest that only specific compounds and specificcombinations thereof and concentrations improve the cohesive strengthproperties induced by ORC fibers.

Example 3: The Hemostatic Effect of Different Compositions in an Ex-VivoModel

In this Example, an exemplary composition with high cohesive strengthaccording to the in-vitro tests was examined for its hemostaticcapability in a suture (pre-clinical) ex-vivo model (as described in theMaterial and Methods section). The composition's efficacy was tested inthe form of a powder or as aggregates. Also, the effect of the absenceof calcium from the composition on the hemostatic efficacy wasevaluated.

Powder compaction was carried out as detailed under “Powder compaction”(Material and Methods section); the compacted powder was then subjectedto a step of drying and a step of milling/grounding as detailed under“Capsule drying and milling/grounding”, thereby creating powdergranules/aggregates.

Blood loss volumes before and after composition application on a suturesite were compared in the manner described above (“suture pre-clinicalex-vivo model”).

For these purposes, a powder composition of fine ORC fibers supplementedwith 5.0% CaCl₂, 2.5% PS and 2.5% εACA was tested in both a compactedand non-compacted form; and a compacted composition of fine ORC fiberssupplemented with 5.0% PS and 5.0% εACA (without calcium) was alsoevaluated.

As demonstrated in FIG. 3, there is a general trend of improvedhemostatic efficacy when the powder is compacted milled and sieved intoaggregate form (an increase in % blood loss reduction was observed). Theresults also show the positive contribution of calcium chloride to theefficacy of the ORC powder.

Example 4: The Effect of Compound Concentration Range in the AggregatesComposition on the Hemostatic Efficacy, Determined by In-Vivo Tests

The following example examines the in-vivo hemostatic effect of changingthe concentrations of each of the compounds chosen according to theabove Examples. The results were collected from different pre-clinicalexperiments carried out on a female porcine using a Liver Biopsy Punchin-vivo model as described above. The results of each experiment arepresented in a different table—tables 3, 4 and 5. In this experimentvarious aggregates compositions were tested. The aggregate compositionstested were ORC fibers with or without supplementation with compounds,the concentrations of the compounds are specified in the Tables below.The compound-supplemented aggregates included ORC fibers combinations of10.0% (w/w of the final mixture weight) long ORC fibers (see sizedistribution in table 1A) and 77.5-85.0% fine ORC fibers.

The table lists success rates of complete bleeding arrest/completehemostasis. In each experiment, fine ORC aggregates (without anysupplementation) served as a baseline control to examine the hemostaticefficacy of the supplementation of the compounds to ORC fibers.

TABLES 3, 4 and 5 Complete Hemostasis Rate Obtained After Application ofAggregates Compositions in a Liver Biopsy Punch In-Vivo Model (number ofreplicates in each tested composition ≧3). Composition Ratio CompleteHemostasis Rate Fine ORC 25% 2.5:95 PS:ORC  0% 2.5:95 εACA:ORC 5:92.5CaCl₂:ORC 25% 2.5:92.5 εACA:ORC 5:92.5 CaCl₂:ORC  0% 2.5:92.5 PS:ORC5:90 CaCl₂:ORC 75% 2.5:90 PS:ORC 2.5:90 εACA:ORC Fine ORC  0% 3.5:91.5CaCl₂:ORC  0% 2.5:91.5 PS:ORC 2.5:91.5 εACA:ORC 6.5:88.5 CaCl₂:ORC37.5%   2.5:88.5 PS:ORC 2.5:88.5 εACA:ORC Fine ORC 25% 5:91.5 CaCl₂:ORC20% 1:91.5 PS:ORC 2.5:91.5 εACA:ORC 5:90 CaCl₂:ORC 50% 2.5:90 PS:ORC2.5:90 εACA:ORC 5:87.5 CaCl₂:ORC 40% 5:87.5 PS:ORC 2.5:87.5 εACA:ORC5:91.5 CaCl₂:ORC 20% 2.5:91.5 PS:ORC 1:91.5 εACA:ORC 5:87.5 CaCl₂:ORC60% 2.5:87.5 PS:ORC 5:87.5 εACA:ORC

Results presented in Tables 3-5 reaffirm that each compound is necessaryfor improving the hemostatic efficacy of ORC fibers since a compositionthat contained all three compounds (calcium chloride, PS and εACA) wasnotably superior compared to the other aggregates compositions. Theresults showed that for both PS and εACA a superior supplementationrange is 2.5% to 5.0%. The range in which calcium chloride serves as abeneficial compound is between 5.0% and 6.5% (a cation concentrationrange of 1.363%-1.636% w/w).

The results show that the supplemented ORC is at least 1.5 times moreefficient than ORC alone (37.5% complete hemostasis rate forsupplemented ORC vs. 25% complete hemostasis rate for ORC alone).

Having shown and described various versions in the present disclosure,further adaptations of the methods and systems described herein may beaccomplished by appropriate modifications by one of ordinary skill inthe art without departing from the scope of the present invention.Several of such potential modifications have been mentioned, and otherswill be apparent to those skilled in the art. For instance, theexamples, versions, geometrics, materials, dimensions, ratios, steps,and the like discussed above are illustrative and are not required.Accordingly, the scope of the present invention should be considered interms of the following claims and is understood not to be limited to thedetails of structure and operation shown and described in thespecification and drawings.

1. A hemostatic composition comprising: cellulose-based fibers having asize distribution of D90 of less than 350 μm, and D50 of less than 167μm, the fibers are at a concentration range of 83.5%-90.0% w/w of theentire composition; an omega amino carboxylic acid at a concentrationrange of 2.5%-5.0% w/w of the entire composition; protamine salt at aconcentration range of 2.5%-5.0% w/w of the entire composition; adivalent cation, the cation concentration being 1.3%-1.8% w/w of theentire composition, wherein the composition is in the form of a powderand/or aggregates.
 2. The hemostatic composition according to claim 1,wherein the cellulose-based fibers have a size distribution of D90 ofless than 177 μm and D50 of less than 95 μm.
 3. The compositionaccording to claim 1, wherein the cellulose-based fibers are OxidizedRegenerated Cellulose (ORC) fibers.
 4. The composition according toclaim 1, wherein the omega amino carboxylic acid is Epsilon AminoCaproic Acid (εACA).
 5. The composition according to claim 1, whereinthe protamine salt is protamine sulfate (PS).
 6. The compositionaccording to claim 1, wherein the divalent cation is provided by calciumchloride.
 7. The composition according to claim 1, wherein the omegaamino carboxylic acid is εACA, the the protamine salt is PS, thedivalent cation is provided by calcium chloride; wherein theconcentration ranges of εACA, PS, and calcium chloride are 2.5%-5.0%,2.5%-5.0%, 5.0%-6.5% w/w, respectively, and wherein the remaining weightis contributed by the cellulose-based fibers to a total weight of 100%w/w.
 8. The composition according to claim 1, wherein a gel formed fromthe powder composition upon contact with blood has a resistance of equalto or higher than 10 times that of a gel formed upon contact of acomparative powder composition consisting of Oxidized RegeneratedCellulose (ORC) with blood; and/or wherein a gel formed from theaggregates composition has a hemostatic capability of equal to or higherthan 1.5 times that of a gel formed upon contact of a comparativeaggregates composition consisting of ORC with blood.
 9. The compositionaccording to claim 1, wherein the composition is in the form ofaggregates having a size in the range of 75 μm-420 μm.
 10. A method formaking a hemostatic composition comprising the steps of: mixingcellulose-based fibers having a size distribution of D90 of less than350 μm, and D50 of less than 167 μm, the fibers being at a concentrationrange of 83.5%-90% w/w of the entire composition with the followingpowder compounds: i—an omega amino carboxylic acid at a concentrationrange of 2.5%-5.0% w/w of the entire composition; ii—protamine salt at aconcentration range of 2.5%-5.0% w/w of the entire composition; andiii—a divalent cation, the cation concentration being 1.3%-1.8% w/w ofthe entire composition.
 11. The method according to claim 10, whereinthe fibers have a size distribution of D90 of less than 177 μm, and D50of less than 95 μm.
 12. A hemostatic composition obtainable according tothe method of claim.
 13. The method according to claim 10, furthercomprising the steps of: compacting the hemostatic composition,optionally subjecting the compacted composition to drying, and sizereduction, thereby obtaining hemostatic aggregates.
 14. A hemostaticaggregates composition obtainable according to the method of claim 13.15. A method for forming a gel comprising the step of: contacting ahemostatic powder and/or aggregates composition according to claim 1, 12or 14 with blood, thereby forming a gel.
 16. The method according toclaim 15, wherein when the contacting is carried out with the powdercomposition, the formed gel has a resistance of equal to or higher than10 times that of a gel formed upon contact of a comparative powdercomposition consisting of Oxidized Regenerated Cellulose (ORC) withblood; and/or wherein when the contacting is carried out with theaggregates composition, the formed gel has a hemostatic capability ofequal to or higher than 1.5 times that of a gel formed upon contact of acomparative aggregates composition consisting of ORC with blood.
 17. Agel obtainable by the method according to claim
 15. 18. A kit comprisinga container including a hemostatic composition according to claim 1, 12or 14 and optionally an applicator, carrier and/or instructions for use.19. A method of treating a bleeding wound; a bacterial infection at awound site, minimizing or preventing a leak from an anastomotic site;sealing a leak at a site and/or preventing adhesion at a surgery site ina subject in need, the method comprising applying an effective amount ofthe hemostatic composition according to claim 1, 12 or 14 onto and/orinto the wound and/or site of the subject.
 20. The method according toclaim 19, wherein the application is carried out without applyingpressure on the composition towards the wound and/or site.